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A recent meta-analysis has summarized the current state of our knowledge regarding the influence of exposure to thin media ideals and:

body image dissatisfaction;

internalization of the thin ideal; and

negative eating behaviors and beliefs.

Body Image Dissatisfaction

90 experimental and correlational studies looked for a relationship between exposure to ultra-thin media models and body dissatisfaction. These studies show a small to medium effect size [d=-.28 with a 95% CI of -.21 to -.35]. There are two ways to conceptualize effect sizes. The first is to consider effect size as an average change in percentile ranking.

The normal curve represents the distribution of body satisfaction of women not exposed to the ultra-thin media ideal. The black line shows the mean shift in body satisfaction found in women exposed to this ideal [the shift is to approximately the 39th percentile].

Another ways to conceptualize effect size is as the percent of non-overlap between the two distributions. The d [-.28] indicates a non-overlap of approximately 20% between the two distributions. This relationship is very crudely illustrated below.

Internalization of the Thin Ideal

23 studies examined the relationship between media exposure to the ultra-thin models and the internalization of the thin ideal. The effect size was small to moderate [d = -.39 with a 95% CI of -.33 to -.44], accounting for an approximate shift in the mean from .50 to .65 and to a percent of non-overlap of approximately 26%.

Negative Eating Behaviors/Beliefs

20 studies examined the relationship between media exposure to ultra-thin models and negative eating behaviors and beliefs. The effect size was small to moderate [d = -.30 with a 95% CI of -.24 to -.36] accounting for an approximate shift in the mean from .50 to .38 and to a percent of non-overlap of approximately 21%.

Limitations

The primary limitations of this meta-analysis are:

to date, studies include mostly white subjects,

more prospective studies are needed, and

the impact of the thin media ideal on other variables, such as obesity and self-consciousness, e.g., should be explored.

Prospective studies are still needed in order to fully understand the impact of media exposure on each of these variables. The experimental studies show a direct causal short-term effect and the correlational studies show a similar real-world relationship. The prospective studies are needed to clearly show the strength and causal direction of the long-term, real-world relationships. Preliminary prospective studies suggest that the media does have some causal role.

Grabe, S, Ward, L.M., & Hyde, J.S. (2008). The Role of the Media in Body Image Concerns Among Women: A Meta-Analysis of Experimental and Correlational Studies. Psychological Bulletin. 134, 460-476.

The bulk of contemporary research supports the conclusion that men value beauty in potential long-term partners more than women do. One potential explanation for this sex difference is that men find beauty more rewarding than do women. Several studies have explored the activity in the brain’s reward circuitry when people view beautiful faces. Jasmin Cloutier and colleagues [2008] are the first to report finding evidence of sex differences in this circuitry in response to attractive faces (Fig 1). They found that men showed more activity in the medial orbital frontal cortex (mOFC) than did women.

Multiple studies have clearly connected the mOFC with reward and this study shows a significant sex difference in mOFC response to attractive faces. The tendency for many will be to interpret the study as showing that men find beauty more intrinsically rewarding than women. The authors caution against drawing this conclusion too quickly. As they point out, it is premature to conclude that men find beauty more rewarding. We do not yet know precisely what role the mOFC plays in the reward circuitry. For example, Kim et.al. (2007) found evidence that the mOFC may be involved in a slower and more accurate deliberative decision-making system that is appended to the more automatic processing done in the nucleus accumbens (NAC) – a part of the reward system that did not show sex differences in Cloutier’s study.

It may be that while men and women were given the same instructions in this study: ‘Using a 1-4 scale, rate faces on how attractive they are.’ they may actually have been performing different activities. Women may have been responding automatically or aesthetically. Men, in addition, may have been attempting to evaluate who to approach, or who might be more receptive, etc. Until we have a clearer understanding of the mOFC’s role in this sort of task, we cannot be sure about how to understand this difference.

There is one methodological issue that I have not been able to evaluate from the article. The facial stimuli used in this study displayed either a neutral expression or a slight smile and the researchers do report equating the faces. As a technical point, I am curious about the exact nature of the equating. Since faces with slight smiles have been shown to elicit increased activity in the mOFC (O’Doherty et.al., 2003) it is important to know that the ratio of neutral to smiling expressions was identical in the photographs of the men and women used as stimuli.

This is a study worth reading – and one to track in RSS feeds and citation indexes!